This invention relates generally to a motor vehicle leveling assembly, and, more particularly, to such an assembly that analyzes the attitude of a motor vehicle in two axes and uses leveling devices to correct the vehicle attitude to a relative reference attitude.
The prior art includes automatic motor vehicle leveling systems; at least one of which requires only a single switch actuation to level an automotive vehicle such as a recreation vehicle (RV). Automatic leveling systems generally include some type of controller that extends and contracts each of a plurality of levelers until at least a portion of the vehicle is level. In most systems there are four levelers or xe2x80x9cjacksxe2x80x9d typically mounted adjacent the four corners of a vehicle, respectively.
For example, U.S. Pat. No. 5,143,386 issued Sep. 1, 1992 to Uriarte, discloses a motor vehicle leveling assembly including an automatic leveling system that includes a controller that selectively extends and contracts four jacks located adjacent the four corners of a vehicle. The controller includes a proportional tilt sensor that provides output signals corresponding to the degree of tilt of separate axes extending between the jacks. The controller responds to the output signals by energizing the jacks to extend or contract independently at a rate proportional to the tilt along the respective axes. The controller can also energize at least two of the jacks to extend or contract simultaneously to increase the speed of leveling. The Uriarte assembly levels a vehicle by first sensing the degree of vehicle tilt along a pair of diagonal axes that are disposed parallel to lines that extend through diagonally opposite jacks. At least two jacks are then simultaneously and independently expanded in response to outputs from sensors at the lowest corners of the vehicle. The controller expands the jacks at a rate proportional to the degree of tilt in their respective axes as indicated by the output of the tilt sensor.
However, a leveling system constructed according to the Uriarte patent is unable to tailor jack extension rates to respond to vehicle dynamics, cannot measure jack extension without relying on inputs from sensors located in the jacks, and cannot determine vehicle attitude change speed without measuring individual jack extension and contraction. The Uriarte system is also not designed to control tilt rate by changing jack drive rates dynamically and cannot change the jack drive rates based upon inputs other than tilt angle. The Uriarte leveler also cannot automatically select between alternative jack grounding procedures based on vehicle conditions (initial attitude of vehicle) and cannot determine jack ground contact without discrete pressure sensors. Uriarte also did not contemplate automatic selection between alternative leveling algorithms based on vehicle and ground conditions. Neither does the Uriarte system level in pairs parallel to longitudinal pitch and lateral roll (rather than diagonal) vehicle axes. The Uriarte system also lacks a means for maximizing signal stability based on rate of angular change and estimated signal noise. The Uriarte leveling system also does not allow an operator a choice between fully automatic and semi automatic leveling operations and includes no provision to automatically correct long term vehicle attitude changes that occur after initial leveling is complete. Still further, the Uriarte system is only able to accurately level whatever portion of the vehicle is supporting the tilt sensor.
What is needed is an improved motor vehicle leveling assembly that overcomes the shortcomings of prior art leveling systems.
A leveling assembly is provided for analyzing the attitude of a structure such as a motor vehicle in two axes and using leveling devices to correct the attitude of the structure relative to a calibrated reference point or attitude. The leveling assembly includes a controller configured to connect to the leveling device and a proportional two-axis tilt sensor connected to the controller. The tilt sensor is configured to be supported on the structure to be leveled and to provide analog signals to the controller representing the degree of longitudinal pitch and lateral roll of the structure the sensor is connected to. The controller is additionally configured to receive and use those signals to determine the attitude of the structure relative to a calibrated sensitivity factor and a user-defined zero point. This allows an operator or installer to determine which portion of the structure will be corrected to a predetermined attitude (such as level) relative to gravity without regard to the location of the tilt sensor and allows an installer to mount the tilt sensor at any point on the structure.
According to another aspect of the invention, a method is provided for analyzing the attitude of a structure relative to two axes. The method includes providing a structure to be leveled that includes a first set of at least two levelers and a second set of at least two levelers actuable to level the structure relative to a calibrated reference attitude. A leveling assembly is also provided that includes a tilt sensor supported on the structure to be leveled. It is then determined whether the structure is in an initial attitude that is within an initial allowable range of attitudes from which the levelers will be able to level the structure. All the levelers are then retracted and one of the first and second sets of levelers is extended it contacts the ground. The other set of levelers is then extended until it also contacts the ground. Each individual leveler is then extended in a predetermined order until each leveler is applying a predetermined minimum force value to the ground. It is then determined about which of the two axes the structure is most out of level and each individual leveler is extended in a predetermined order until the structure is level about that axis. The individual levelers are then extended a predetermined order until the structure is level about the other of the two axes.
According to another aspect of the invention, a method is provided for maintaining a structure in a level attitude after initial leveling of the structure where levelers capable of leveling the structure are mounted on the structure. The method includes providing a leveling assembly on the structure and monitoring the attitude of the structure by monitoring signals from a tilt sensor of the leveling assembly. The structure is then leveled by actuating the levelers in response to signals from the tilt sensor that indicate an out-of-level attitude of greater than a predetermined magnitude has existed for longer than a predetermined period of time.
According to another aspect of the invention, a method for analyzing the attitude of a structure relative to two axes is provided that includes providing a structure to be leveled that includes first and second sets of levelers actuable to change the attitude of the structure relative to a calibrated reference attitude. A leveling assembly is then provided on the structure and it is determined whether the structure is in an initial attitude that is within an initial allowable range of attitudes from which the levelers will be able to level the structure. The levelers are then retracted and one set of levelers is extended until it contacts the ground. The other set of levelers is then extended until it contacts the ground. The levelers are then extended individually, in a predetermined order, until each leveler is applying a predetermined minimum force value to the ground. It is then determined which of the two axes need to be leveled and an operator is provided with a visual indication of the axes about which the structure is out-of-level. It is then determined about which of the two axes the structure is most out-of-level and the operator is provided with a visual indication of a first axis about which the structure is most out-of-level. The structure is then leveled about the first axis by operating appropriate levelers in response to an operator input. If the structure is also out-of-level about the remaining axis, the structure is leveled about that axis by operating appropriate levelers in response to an operator""s input.
According to another aspect of the invention, a method is provided for calibrating a leveling assembly to recognize when a structure the assembly is installed on is level relative to gravity. This method includes providing a structure to be leveled that includes levelers actuable to change the attitude of the structure. A leveling assembly is provided on the structure and includes a controller and a tilt sensor. The controller is programmed to include a zero mode in which the controller is ready to receive a signal that will instruct the controller to recognize signal values being received from the tilt sensor as indicating that the structure is level. A level indicator is provided at a desired location on the structure. The level indicator is configured indicate when it is level relative to gravity. The levelers are then actuated until the level indicator indicates that the level indicator is level relative to gravity. An input is then provided to the controller indicating that the current set of signals being received from the tilt sensor is the set of signal values that will represent the correct attitude for the controller to reference in future leveling operations.